“IITYWIMWYBMAD” or “IITYWIM WYBMAD” (“If I tell you what it means, will you buy me a drink?”) is a texting initialism that has been printed on many gift items, such as T-shirts, hats and bumper stickers. “IITYWIMWYBMAD If I tell you what it means, will you buy me a drink?” has been cited in print since at least 1993.
     
 
Google Groups: alt.best.of.internet
Commonly Used Abbreviations
Richard Osterberg
4/16/93
(...)
IITYWIMIWHTKY If I tell you what it means, I will have to kill you
IITYWIMWYBMAD If I tell you what it means, will you buy me a drink?
     
Google Groups: maus.rec.sf
Tiptree
Björn Spruck
2/26/96
(...)
IITYWTMWYKM - If I Tell You What This Means Will You Kiss Me?
IITYWIMWYBMAD- If I Tell You What It Means Will You Buy Me A Drink?
ILSHIBAMF   - I Laughed So Hard I Broke All My Furniture!
IMHO       - In My Humble Opinion
IMNSHO     - In My Not So Humble Opinion
IMO       - In My Opinion
IMRO       - In My Royal Opinion
INPO       - In No Particular Order
IOW       - In Other Words
 
Urban Dictionary
IITYWYBMAD
An acronym for “If I Tell You Will You Buy Me A Drink.” One usually has IITYWYBMAD printed somewhere where nosey people can read it and subsequently be suckered into buying one a drink.
Bob: What does IITYWYBMAD mean?
Sam: If I Tell You Will You Buy Me A Drink?
Bob: Hmm… Alright you cheap bastard! What does it mean?
Sam: If I Tell You Will You Buy Me A Drink?
by leveller225 September 15, 2004
 
Google Books
Transl8it! Dxnre & Glosre:
Yor Complet Guid 2 Onlin Ch@ & Sms Txt Lngo
By Dan Wilton
New York, NY: iUniverse
2005
Pg. 30:
IITYWITIWYBMAD if i tell you what it means will you buy me a drink
 
Twitter
8.0.Cinco
‏@strangetikigod
“IITYWIMWYBMAD”
10:50 PM - 13 May 2008
 
Twitter
Neil K Carroll
‏@nickelcitygraph
Check out the latest post on the Nickel City Graphics Blog - IITYWIMWYBMAD? - http://bit.ly/lbFq5
11:52 AM - 14 Sep 2009
 
Twitter
Deal Nay
‏@dealnaydotcom
IITYWIMWYBMAD? Men?s T-Shirt - These men’s novelty t-shirts give the term “bar wear” a… http://dealnay.com/113907
8:43 AM - 19 Oct 2009
   
Google Books
Texting Instant Message and Internet Slang
By Ray Myers, Jr.
Maple Valley, WA; PocketCrib, LLC
2014
Pg. ?:
IITYWIMWYBMAD If I tell you what it means, will you buy me a drink?
     
Washington (DC) Post
The FBI maintains an 83-page glossary of Internet slang. And it is hilariously, frighteningly out of touch.
By Caitlin Dewey June 17, 2014
(...)
Among the other head-scratching terms the FBI considers can’t-miss Internet slang:
(...)
12. IITYWIMWYBMAD (“if I tell you what it means will you buy me a drink?”) — 250 tweets